Film-Tech Forum ARCHIVE: Metric Ultrasonic Spicer Modification Question

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Posted by Mitchell Dvoskin (Member # 751) on 06-28-2012, 08:57 AM:

In my travels, I recently acquired a Metric Ultrasonic Film Splicer. It works great, but my understanding is that they only work on polyester film stocks.

I have read conflicting things on the internet as too whether these can be modified to work on acetate film stocks.

Can these be modified to work on acetate film stocks? If so, is it something that I can modify, or was it a factory only change?

Posted by Richard P. May (Member # 3598) on 06-28-2012, 10:06 AM:

Mitchell,
Over 20 years ago, when Turner took over the MGM library, we acquired a Metric splicer from the MGM editorial department. I used it for everything successfully. Not until getting into the restoration lab end of the business was I informed that it isn't supposed to work with acetate.
In practice, we only use ultrasonic for polyester film, and that is the majority of our use, putting together the A and B sections of reels of new prints, etc. We continue to use conventional cement splicers for precise work on other film types.
Adjusting the Metric splicer is no big deal, and certainly does not need "factory" modification. There is really nothing to modify except the speed at which the anvil moves across the splice. If too fast, it won't weld the film together, and if too slow the splice is messy. Just take off the top (an Allen screw on each side must be removed), and you will see a speed adjustment dial. This can be adjusted to make the best and neatest splice to your satisfaction.
I must add, in spite of what I said above about using Metric for everything, do some testing to be sure it works for you on acetate. It can weaken the splice if not done properly.
Also, the splices will have some edge material that is from the film's melting together. This must be removed with small scissors, or the splice can bump sideways going thru the projector.

Posted by Dave Macaulay (Member # 813) on 06-28-2012, 10:15 PM:

You can also adjust the roller pressure. There's a small allen set screw on the travelling arm, you have to cycle the thing and turn it off with the arm out to get access I think. This is super sensitive, 1/8 turn is a lot.
The mechanical adjustments both affect the splice quality. It's been a long time but I used to service the 70mm ones a lot. The arm travel back (with ultrasonic on) was set to about 20 seconds for 70mm as I recall. travel out is full speed, travel speed back in is adjustable. The rack and pinion assembly is often mechanically misaligned causing a jerky movement, that messes with splice quality.
Never cycle it without film. The horn surface will be damaged without the film "cushion" and I've seen horns cracked from the internal stress of running without film.
The splice area should be a thin stripe of completely fused plastic, with a ridge/edge of melted plastic squeezed out the sides of the welded area,. The pressure adjustment interacts with the pass time but too much pressure will give a thin weak weld strip, it should be equal or slightly thicker than the film is.
There is an adjustment on the oscillator/power board assembly but this should be left alone. It''s easy to misadjust it and that gives weak welds and overheats the power transistors. The adjustment if needed requires a cheater cord with an ammeter in series: you tune it for minimum line current as I recall, that's when the power circuit is in tune with the mechanical resonance of the horn and transducer.
I set the pressure with the splicer working, as it is tightened there's a point where the bearing spins rapidly and the sound is even. Too much pressure and the sound gets strained, too little and the bearing doesn't spin.
I've tried acetate, it will weld but not really nicely. possibly the unit could be adjusted for perfect welds with acetate but then it would be poor for polyester. And you can use cement on acetate...